The Holy Grail War is a battle royale amongst 7 magi who serve as Masters. Masters, through making use of the command seals they are offered when they get in the war, command Heroic Spirits called Servants to fight for them in battle. In the Fifth Holy Grail War, Rin Tohsaka is among the magi going into the competitors. With her Servant, Archer, she intends to obtain the ultimate prize– the Holy Grail, a magical artifact capable of giving its wielder any wish.

One of Rin’s classmates, Emiya Shirou, accidentally gets in the competition up commanding a Servant of his own known as Saber. As they find themselves facing mutual opponents, Rin and Shirou choose to form a temporary alliance as they challenge their opponents in the Holy Grail War.